Short-chain polyphosphates: Extraction effects on migration and size estimation of Saccharomyces cerevisiae extracts with polyacrylamide gel electrophoresis.

Polyacrylamide gel electrophoresis is commonly used to characterize the chain length of polyphosphates (polyP), more generally called condensed phosphates. After separation, nonradioactive, optical polyP staining is limited to chain lengths greater than 15 PO 3 - ${\rm{PO}}_3^ - $ monomers with toluidine blue or 4',6-diamidino-2-phenylindole. PolyP chain lengths longer than 62 PO 3 - $\;{\rm{PO}}_3^ - $ monomers were correlated to the shortest DNA ladders. In this study, synthetic linear polyPs (Sigma-Aldrich "Type 45", estimated mean length of 45 PO 3 - ${\rm{PO}}_3^ - $ monomers), trimetaphosphate (trimetaP: 3 PO 3 - ${\rm{PO}}_3^ - $ ring), tripolyphosphate (tripolyP), pyrophosphate (PPi ), and inorganic orthophosphate (o-Pi ) were visualized after separation by an in situ hydrolytic degradation process to o-Pi that was subsequently stained with methyl green. Statistically insignificant migration reduction of synthetic short-chain polyP after perchloric acid or phenol-chloroform extraction was confirmed with the Friedman test. 31 P diffusion-ordered NMR spectroscopy confirmed that extraction also reduced PPi diffusivity by <10%. Linear regression between the Rf peak migration value and the logarithm of synthetic polyP molecular weights enabled estimation of extracted polyP chain lengths from 2 to 45 PO 3 - ${\rm{PO}}_3^ - $ monomers. Linear polyP extracts from Saccharomyces cerevisiae grown in aerobic conditions were generally shorter than extracts cultured in anaerobic conditions. Extractions from both aerobic and anaerobic S. cerevisiae included tripolyP and o-Pi , but no PPi .

Extraction processes reduce polyphosphate ion migration, dispersion and diffusion as detected with gel electrophoresis and 31 P DOSY NMR.

Inorganic polyphosphates (polyPs) have been identified in eukaryotic and prokaryotic cells alike. Various extraction methods have been optimized as a necessary step before identification and measurement of these polymers. Three commercially available sodium polyP glasses were either dissolved or dissolved and extracted by two commonly used polyP extraction techniques - perchloric acid or buffered phenol-chloroform. The products were separated by polyacrylamide gel electrophoresis (PAGE), stained with toluidine blue O, and the migration results quantitatively compared. Both extraction processes reduced the relative migration distances of the peak and leading edges, and the stained band lengths, suggesting reduced polyP migration and dispersion. 31 P diffusion-ordered spectroscopy nuclear magnetic resonance confirmed that polyP extraction by perchloric acid or phenol-chloroform processes reduced polyP diffusion coefficients and suggested hydrolytic degradation with stronger end-chain signals. Reduced polyP diffusivity after extraction makes possible an overestimation of synthetic polyP chain length assignment when compared to unextracted polyP ladders with PAGE. The mechanism(s) for reduced synthetic polyP diffusion after extraction and intracellular chemical environment effects on migration are not known.

Risk Factors for Alzheimer Disease Development After Traumatic Brain Injury: A Preliminary Study.

Traumatic brain injury (TBI) is increasingly recognized as a major risk factor for developing neurocognitive disorders, though this association remains controversial. Determination of risk factors for post-traumatic neurodegeneration in patients with TBI is critical given the high incidence of TBI. We hypothesized that cardiovascular and metabolic comorbidities, in addition to TBI severity, are associated with the risk of post-traumatic development of Alzheimer disease dementia (ADD). A case-controlled retrospective study was conducted using medical records and medical insurance data of 5642 patients with TBI admitted to a tertiary trauma center over a 12-year period, to assess risk factors of developing ADD after TBI. Logistic regression shows that presence of post-traumatic amnesia ( P= 0.03) and chronic vascular lesions ( P= 0.04) are significantly associated with development of ADD after TBI. This innovative preliminary study is the first to explore risk factors for post-traumatic ADD. Further association studies are essential to optimize care following TBI.

Prevalence of midline cervical spine tenderness in the non-trauma population.

OBJECTIVE: The Canadian C-Spine Rule (CCR) and the National Emergency X-Radiography Utilization Study (NEXUS) criteria are two commonly used clinical decision rules which use midline cervical spine (c-spine) tenderness on palpation as an indication for c-spine imaging post-trauma. This study was undertaken to determine the prevalence and location of midline c-spine tenderness in the non-trauma population. METHODS: We prospectively evaluated consenting adult patients presenting to an urban ED or university sport medicine clinic in Montreal, Canada between 2018 and 2020 for atraumatic non-head and neck-related reports over a 20-month period. The presence and location of pain during midline c-spine palpation as assessed by two examiners during separate evaluations was recorded. Patient information such as age, neck length and circumference, gender, body mass index (BMI) and scaphoid tenderness was also collected. RESULTS: Of 478 patients enrolled, 286 (59.8%) had midline c-spine tenderness on palpation with both examiners. The majority of those with tenderness were female (70.6%). When examining all patients, tenderness was present in the upper third of the c-spine in 128 (26.8%) patients, middle third in 270 (56.5%) patients and lower third in 6 (1.3%) patients. Factors associated with having increased odds of midline c-spine tenderness on palpation included a lower BMI and the presence of scaphoid tenderness on palpation. CONCLUSIONS: There is a high prevalence of c-spine tenderness on palpation in patients who have not undergone head or neck trauma. This finding may help explain the low specificity in some of the validation studies examining the CCR and the NEXUS criteria.

A New In-Skates Balance Error Scoring System for Ice Hockey Players.

OBJECTIVE: Evaluate a new in-skates balance error scoring system (SBESS) for ice hockey players wearing their equipment. DESIGN: Prospective, randomized, single blinded study. SETTING: Sport Medicine Clinic. PARTICIPANTS: Eighty university hockey players. INTERVENTION: A control group performed the SBESS assessment at rest on 2 separate occasions and an experimental group performed the assessment at rest and after exertion. The SBESS consists of maintaining different stances on ice skates for 20 seconds each, while wearing full equipment (no stick, gloves and helmet) and standing on a hard rubber surface. Three independent reviewers scored the video recorded assessments. MAIN OUTCOMES MEASURES: Primary outcome was the number of balance errors and the secondary outcome was the number of falls. RESULTS: The control group's median SBESS scores were 2 and 3 on the first and second attempts at rest, respectively. The experimental group's median SBESS scores were 2 at rest and 2 after exertion. There was no fatigue effect and no athletes fell while performing the test. Of the 4 stances tested, the tandem stance had the highest variability in error scores between athletes and when repeated by the same athlete. The intraclass correlation coefficient (ICC) for interrater reliability was above 0.82, and the intrarater reliability ICC was above 0.86 for all SBESS scores. There was no concordance between the SBESS and the modified BESS. CONCLUSIONS: The SBESS, omitting the tandem stance, is a safe and reproducible sideline balance assessment of ice hockey players wearing full equipment.

Do Mountain Bikers Know When They Have Had a Concussion and, Do They Know to Stop Riding?

OBJECTIVE: To establish the prevalence of concussions in mountain bikers and to determine factors that increase their risk of concussion. Secondary objectives include determination of whether mountain bikers have undiagnosed concussions, continue to ride after experiencing concussion symptoms, and if they knowingly ride with a broken helmet. DESIGN: Retrospective survey. SETTING: Seven-day mountain bike stage race. PARTICIPANTS: Two hundred nineteen mountain bikers. MAIN OUTCOME MEASURES: Number of rider concussions diagnosed, number of riders experiencing concussion symptoms without diagnosed concussions, number of riders who continue to ride after experiencing a concussion symptom, and number of riders who rode with a broken helmet. INDEPENDENT VARIABLES: The independent variables studied included age, gender, nationality, number of times riding in past year, style of riding (cross-country, downhill, or freeride), years mountain biking, years mountain bike racing, whether they are a sponsored cyclist, and whether they also ride a road bike. RESULTS: Fifteen of 219 mountain bikers (6.9%) had a diagnosed concussion after being hit in the head while mountain biking within the past year, with older riders having a decreased risk [odds ratio (OR), 0.91; P = 0.04], and sponsored riders having a 5-fold increased risk compared with nonsponsored riders (OR, 4.20; P = 0.05). Twenty-eight riders (12.8%) experienced a concussion symptom without being diagnosed with a concussion and 67.5% of the riders who experienced a concussion symptom continued to ride afterward. Overall, 29.2% of riders reported riding with a broken helmet. CONCLUSIONS: The yearly prevalence of diagnosed concussions in mountain bikers is 6.9%. More than one-third of mountain bikers do not recognize when they have had a concussion and continue riding after experiencing concussion symptoms or with a broken helmet. These behaviors increase their risk of worsening concussion symptoms and acquiring a second injury.

Cognitive-communication skills and acute outcome following mild traumatic brain injury.

PURPOSE: Little is known about cognitive-communication skills post mild traumatic brain injury (mTBI). We aimed to determine how performance on cognitive-communication measures in the acute recovery period relates to early outcome following complicated mTBI. METHOD: Results of language and communication skill measures, demographic and accident-related data, length of stay (LOS), Glasgow Outcome Scale-Extended (GOSE) scores and discharge destinations were retrospectively gathered for 128 admitted patients with complicated mTBI. RESULTS: More than half of the individuals required rehabilitation services post discharge from hospital with over a third needing in-patient rehabilitation. Patients with poorer skills in auditory comprehension, verbal reasoning, confrontation naming, verbal fluency and conversational discourse were more likely to require in-patient rehabilitation. Subjects with worse skills in naming, conversational discourse and letter-category verbal fluency had a greater chance of being referred to out-patient rehabilitation services. Thus patients with both auditory comprehension and oral expression deficits were more likely to require in-patient services whereas those who had oral expression deficits but no significant difficulty in auditory comprehension were more often referred to out-patient services. Also, worse conversational discourse skills and semantic-category naming ability were related to lower GOSE scores and the chance of a longer LOS was greater when letter-category naming was poorer. CONCLUSION: The likelihood of individuals requiring rehabilitation services post mTBI was related to performance on several oral expression and auditory comprehension measures. It is therefore important to evaluate cognitive-communication skills early to determine rehabilitation needs.

Oral Hypertonic Saline Is Effective in Reversing Acute Mild-to-Moderate Symptomatic Exercise-Associated Hyponatremia.

OBJECTIVES: To determine whether oral administration of 3% hypertonic saline (HTS) is as efficacious as intravenous (IV) 3% saline in reversing symptoms of mild-to-moderate symptomatic exercise-associated hyponatremia (EAH) in athletes during and after a long-distance triathlon. DESIGN: Noninferiority, open-label, parallel-group, randomized control trial to IV or oral HTS. We used permuted block randomization with sealed envelopes, containing the word either "oral" or "IV." SETTING: Annual long-distance triathlon (3.8-km swim, 180-km bike, and 42-km run) at Mont-Tremblant, Quebec, Canada. PARTICIPANTS: Twenty race finishers with mild to moderately symptomatic EAH. INDEPENDENT VARIABLES: Age, sex, race finish time, and 9 clinical symptoms. MAIN OUTCOME MEASURES: Time from treatment to discharge. METHODS: We successfully randomized 20 participants to receive either an oral (n = 11) or IV (n = 9) bolus of HTS. We performed venipuncture to measure serum sodium (Na) at presentation to the medical clinic and at time of symptom resolution after the intervention. RESULTS: The average time from treatment to discharge was 75.8 minutes (SD 29.7) for the IV treatment group and 50.3 minutes (SD 26.8) for the oral treatment group (t test, P = 0.02). Serum Na before and after treatment was not significantly different in both groups. There was no difference on presentation between groups in age, sex, or race finish time, both groups presented with an average of 6 symptoms. CONCLUSIONS: Oral HTS is effective in reversing symptoms of mild-to-moderate hyponatremia in EAH.

Simulation in Learning and Using the Nutrition Care Process/Terminology: Experiences and Perceptions of Dietitians in Canada.

Purpose: To investigate experiences with, and perceptions of, simulation in learning and using the Nutrition Care Process/Terminology (NCP/T) of dietitians in Canada. Methods: In February-March 2017, a convenience sample of 382 dietitians in Canada (71.8% in clinical practice) completed an online survey regarding the type(s), setting(s), and perceptions of the simulations in which they engaged in learning and using the NCP/T. Results: A majority (76.7%) of respondents had engaged in NCP/T-related simulation, most commonly case studies (85.3%) and role-play (42.0%), as part of workplace/volunteer training (51.4%) and undergraduate internship/stage/practicum (34.2%). Nearly half (49.5%) of respondents learned all 4 NCP components via simulation, with Nutrition Diagnosis being the most common individual component (57%). Over three-quarters of respondents agreed/strongly agreed that simulation helped them better understand/use the NCP/T and that NCP/T-related knowledge/skills gained through simulation are transferable to the clinical setting/dietetic practice. Conclusions: Dietitians in Canada perceive simulation to have helped them learn and use the NCP/T. Resources should be directed at further developing simulation for teaching the NCP/T in dietetics education and training. Research investigating characteristics, barriers, and facilitators of effective NCP/T-simulation, using objective (vs. perceived) learning outcome measures is needed.

Bioimpedance-measured volume overload predicts longer duration of mechanical ventilation in intensive care unit patients.

PURPOSE: Bioelectrical impedance analysis (BIA) is a technology that provides a rapid, non-invasive measurement of volume in body compartments and may aid the physician in the assessment of volume status. We sought to investigate the effect of BIA-measured volume status on duration of mechanical ventilation, 28-day mortality, and acute kidney injury requiring renal replacement therapy in a population of medical/surgical patients admitted to the intensive care unit (ICU). METHODS: Prospective observational study of adult patients who required mechanical ventilation within 24 hr of admission to ICU. Bioelectrical impedance analysis measured extracellular water (ECW) and total body water (TBW) and these measurements were recorded on days 1, 3, 5, and 7. RESULTS: A total of 36 patients were enrolled. Mean (standard deviation) age was 61.8 (21.3) years and 31% of patients were female. The majority were admitted from the emergency department or operating room. The most common diagnosis was sepsis. At 28 days, eight patients (22%) had died. There was no association between ECW/TBW ratio at day 1 and 28-day mortality (odds ratio, 1.2; 95% confidence interval [CI], 0.6 to 2.3) after adjusting for age, sex, and Acute Physiology and Chronic Health Evaluation II score. The median [interquartile range] number of ventilator days was 5 [2.5-7.5]. On day 1, for each 1% increase in the ECW/TBW ratio, there was a 1.2-fold increase in ventilator days (95% CI, 1.003 to 1.4; P = 0.05). It is notable that 20% of eligible patients could not be enrolled because medical equipment interfered with correct electrode placement. CONCLUSION: Bioimpedance-measured ECW/TBW on day 1 of admission to the ICU is associated with time on the ventilator. While this technology may be a useful adjunct to the clinical assessment of volume status, there are technical barriers to its routine use in a general ICU population.

Why Professional Football Players Chose Not to Reveal Their Concussion Symptoms During a Practice or Game.

OBJECTIVE: To determine why professional football players in Canada decided not to seek medical attention during a game or practice when they believed they had suffered a concussion. DESIGN: Retrospective survey. SETTING: Preseason Canadian Football League training camps. PARTICIPANTS: Four hundred fifty-four male professional football players. MAIN OUTCOME MEASURES: Reasons athletes did not seek medical attention for a presumed concussion during the previous season, how often this occurred and how important these reasons were in the decision process. RESULTS: One hundred six of the 454 respondents (23.4%) believed they had suffered a concussion during their previous football season and 87 of the 106 (82.1%) did not seek medical attention for a concussion at least once during that season. The response "Did not feel the concussion was serious/severe and felt you could still continue to play with little danger to yourself" was the most commonly listed reason (49/106) for not seeking medical attention for a presumed concussion. Many players answered that they did not seek medical attention because they did not want to be removed from a game (42/106) and/or they did not want to risk missing future games (41/106) by being diagnosed with a concussion. CONCLUSIONS: Some professional football players who believed they had suffered a concussion chose not to seek medical attention at the time of injury. Players seemed educated about the concussion evaluation process and possible treatment guidelines, but this knowledge did not necessarily translate into safe and appropriate behavior at the time of injury.

Psychogenic nonepileptic seizures in patients with surgically treated temporal lobe epilepsy: Presurgical and de novo postsurgical occurrence.

Whether occurring before or after an epilepsy surgery, psychogenic nonepileptic seizures (PNES) impact treatment options and quality of life of patients with epilepsy. We investigated the frequency of pre- and postsurgical PNES, and the postsurgical Engel and psychiatric outcomes in patients with drug-resistant temporal lobe epilepsy (TLE). We reviewed 278 patients with mean age at surgery of 37.1±12.4years. Postsurgical follow-up information was available in 220 patients, with average follow-up of 4years. Nine patients (9/278 or 3.2%) had presurgical documented PNES. Eight patients (8/220 or 3.6%) developed de novo PNES after surgery. Pre- and postsurgery psychiatric comorbidities were similar to the patients without PNES. After surgery, in the group with presurgical PNES, five patients were seizure-free, and three presented persistent PNES. In the group with de novo postsurgery PNES, 62.5% had Engel II-IV, and 37.5% had Engel I. All presented PNES at last follow-up. Presurgical video-EEG monitoring is crucial in the diagnosis of coexisting PNES. Patients presenting presurgical PNES and drug-resistant TLE should not be denied surgery based on this comorbidity, as they can have good postsurgical epilepsy and psychiatric outcomes. Psychogenic nonepileptic seizures may appear after TLE surgery in a low but noteworthy proportion of patients regardless of the Engel outcome.

Denervation drives mitochondrial dysfunction in skeletal muscle of octogenarians.

KEY POINTS: Mitochondria are frequently implicated in the ageing of skeletal muscle, although the role of denervation in modulating mitochondrial function in ageing muscle is unknown. We show that increased sensitivity to apoptosis initiation occurs prior to evidence of persistent denervation and is thus a primary mitochondrial defect in ageing muscle worthy of therapeutic targeting. However, at more advanced age, mitochondrial function changes are markedly impacted by persistent sporadic myofibre denervation, suggesting the mitochondrion may be a less viable therapeutic target. ABSTRACT: Experimental denervation modulates mitochondrial function, where changes in both reactive oxygen species (ROS) and sensitivity to permeability transition are implicated in the resultant muscle atrophy. Notably, although denervation occurs sporadically in ageing muscle, its impact on ageing muscle mitochondria is unknown. Because this information has important therapeutic implications concerning targeting the mitochondrion in ageing muscle, we examined mitochondrial function in skeletal muscle from four groups of humans, comprising two active (mean ± SD age: 23.7 ± 2.7 years and 71.2 ± 4.9 years) and two inactive groups (64.8 ± 3.1 years and 82.5 ± 4.8 years), and compared this with a murine model of sporadic denervation. We tested the hypothesis that, although some alterations of mitochondrial function in aged muscle are attributable to a primary organelle defect, mitochondrial dysfunction would be impacted by persistent denervation in advanced age. Both ageing in humans and sporadic denervation in mice increased mitochondrial sensitivity to permeability transition (humans, P = 0.004; mice, P = 0.01). To determine the contribution of sporadic denervation to mitochondrial function, we pharmacologically inhibited the denervation-induced ROS response. This reduced ROS emission by 60% (P = 0.02) in sporadically denervated mouse muscle, which is similar to that seen in humans older than 75 years (-66%, P = 0.02) but not those younger than 75 years. We conclude that an increased sensitivity to permeability transition is a primary mitochondrial defect in ageing muscle. However, at more advanced age, when muscle atrophy becomes more clinically severe, mitochondrial function changes are markedly impacted by persistent sporadic denervation, making the mitochondrion a less viable therapeutic target.

Outcomes of trocar-guided Gynemesh PS™ versus single-incision trocarless Polyform™ transvaginal mesh procedures.

INTRODUCTION AND HYPOTHESIS: The aim of the study was to compare rates of success, mesh exposure, and surgical re-intervention after trocar-guided Gynemesh PS™ and trocarless Polyform™ transvaginal mesh procedures. METHODS: We conducted a retrospective cohort study of all transvaginal mesh procedures performed at our centers between January 2008 and May 2012. Multiple logistic regression models were used to explore the binary outcomes of objective and subjective success rates, as well as mesh exposure and re-intervention rates, between the two procedures after adjustment for patient's age, parity, body mass index, smoking status, previous hysterectomy, previous prolapse surgery, and follow-up time. RESULTS: We included 103 transvaginal mesh procedures (47 trocar-guided Gynemesh PS™ and 56 trocarless Polyform™). In both groups, Pelvic Organ Prolapse Quantification (POP-Q) scores were significantly improved after the procedure. Median follow-up was 340 days and interquartile range (IQR) 152-644. Objective success rates were 55.3 % (26/47) in the trocar group and 60.7 % (34/56) in the trocarless group (p = 0.9), whereas subjective success was 83.0 % (39/47) and 94.6 % (53/56), respectively (p = 0.1). The adjusted odds of developing mesh exposure were significantly less after trocarless transvaginal mesh procedures compared to trocar-guided ones [odds ratio (OR) 0.16, 95 % confidence interval (CI) 0.03-0.97]. Surgical re-interventions, aimed mostly at treating recurrent prolapse, mesh exposure, and latent stress urinary incontinence, were also significantly less frequent after trocarless procedures [5 patients (8.9 %) requiring re-intervention versus 15 (31.9 %), respectively, adjusted OR 0.15, 95 % CI 0.04-0.60]. CONCLUSIONS: Trocar-guided Gynemesh PS™ and trocarless Polyform™ transvaginal mesh systems result in similar objective and subjective success rates. The newer Polyform™ mesh results in significantly fewer mesh exposures and surgical re-interventions.

Why university athletes choose not to reveal their concussion symptoms during a practice or game.

OBJECTIVE: To determine why athletes decide not to seek medical attention during a game or practice when they believe they have suffered a concussion. DESIGN: A retrospective survey. SETTING: University Sport Medicine Clinic. PARTICIPANTS: A total of 469 male and female university athletes from several varsity team sports were participated in the study. MAIN OUTCOME MEASURES: Athletes were surveyed about the previous 12 months to identify specific reasons why those athletes who believed they had suffered a concussion during a game or practice decided not to seek attention at that time, how often these reasons occurred, and how important these reasons were in the decision process. RESULTS: Ninety-two of the 469 athletes (19.6%) believed they had suffered a concussion within the previous 12 months while playing their respective sport, and 72 of these 92 athletes (78.3%) did not seek medical attention during the game or practice at least once during that time. Sports in which athletes were more likely to not reveal their concussion symptoms were football and ice hockey. The reason "Did not feel the concussion was serious/severe and felt you could still continue to play with little danger to yourself," was listed most commonly (55/92) as a cause for not seeking medical attention for a presumed concussion. CONCLUSIONS: A significant percentage of university athletes who believed they had suffered a concussion chose not to seek medical attention at the time of injury. Improved education of players, parents, and coaches about the dangers of continuing to play with concussion symptoms may help improve reporting. CLINICAL RELEVANCE: Medical staff should be aware that university athletes who believe they have suffered a concussion may choose not to volunteer their symptoms during a game or practice for a variety of personal and athletic reasons.

Reconstruction of rat retinal progenitor cell lineages in vitro reveals a surprising degree of stochasticity in cell fate decisions.

In vivo cell lineage-tracing studies in the vertebrate retina have revealed that the sizes and cellular compositions of retinal clones are highly variable. It has been challenging to ascertain whether this variability reflects distinct but reproducible lineages among many different retinal progenitor cells (RPCs) or is the product of stochastic fate decisions operating within a population of more equivalent RPCs. To begin to distinguish these possibilities, we developed a method for long-term videomicroscopy to follow the lineages of rat perinatal RPCs cultured at clonal density. In such cultures, cell-cell interactions between two different clones are eliminated and the extracellular environment is kept constant, allowing us to study the cell-intrinsic potential of a given RPC. Quantitative analysis of the reconstructed lineages showed that the mode of division of RPCs is strikingly consistent with a simple stochastic pattern of behavior in which the decision to multiply or differentiate is set by fixed probabilities. The variability seen in the composition and order of cell type genesis within clones is well described by assuming that each of the four different retinal cell types generated at this stage is chosen stochastically by differentiating neurons, with relative probabilities of each type set by their abundance in the mature retina. Although a few of the many possible combinations of cell types within clones occur at frequencies that are incompatible with a fully stochastic model, our results support the notion that stochasticity has a major role during retinal development and therefore possibly in other parts of the central nervous system.

Mechanisms of injury for concussions in university football, ice hockey, and soccer.

OBJECTIVE: To examine the mechanisms of injury for concussions in university football, ice hockey, and soccer. DESIGN: Prospective cohort design. SETTING: McGill University Sport Medicine Clinic. PARTICIPANTS: Male and female athletes participating in varsity football, ice hockey, and soccer. MAIN OUTCOME MEASURES: Athletes were followed prospectively over a 10-year period to determine the mechanisms of injury for concussions and whether contact with certain areas of the body or individual variables predisposed to longer recovery from concussions. For soccer, data were collected on whether concussions occurred while attempting to head the ball. RESULTS: There were 226 concussions in 170 athletes over the study period. The side/temporal area of the head or helmet was the most common area to be struck resulting in concussion in all 3 sports. Contact from another player's head or helmet was the most probable mechanism in football and soccer. In hockey, concussion impacts were more likely to occur from contact with another body part or object rather than another head/helmet. Differences in mechanisms of injuries were found between males and females in soccer and ice hockey. Athletes with multiple concussions took longer to return to play with each subsequent concussion. Half of the concussions in soccer were related to attempting to head the soccer ball. CONCLUSIONS: The side of the head or helmet was the most common area to be struck resulting in concussion in all 3 sports. In ice hockey and soccer, there are differences in the mechanisms of injury for males and females within the same sport.

Influence of anthropogenic activities on the trace organic contamination of lakes.

Anthropogenic activities and urbanization can lead to the discharge of organic compounds into surface waters. It is important to investigate these relationships further to mitigate contamination better and prioritize protection efforts. This study aimed to verify the effect of specific anthropogenic factors on lake water contamination caused by trace organic contaminants (TrOCs) such as pharmaceuticals, pesticides and consumer product additives. Data on the detection and concentration levels of 54 TrOCs, major anthropogenic land use, and human activities from a large-scale study on Canadian lakes were used to reach this goal. The association of population and livestock densities, the presence of wastewater treatment plants (WWTPs) and hospitals as well as the agricultural and urban land use in the lakes' watersheds on lake water contamination was investigated by applying negative binomial and ordinal logistic regression models. These models were also controlled for lake/watershed area ratio, lake depth, water, residence time, watershed slope, precipitation, and sampling date. The statistical analysis confirmed that agricultural land use, urban land use, and WWTPs plants in lake watersheds are significantly associated with the number of TrOCs detected (incidence rate ratio > 1, p < 0.001) and the summed concentration of targeted TrOCs (odds ratio > 1, p < 0.001). Agricultural land use (odds ratio = 1.58, p < 0.001) and urban land use (odds ratio = 1.19, p < 0.02) were also significantly associated with the summed concentration of the targeted pesticides. This latter outcome thus suggests that urban centers are also important contributors to the concentration levels of pesticides in lakes. Overall, these results demonstrate that even in complex ecosystems such as lakes, it is possible to use a limited number of factors to explain anthropogenic contamination. This can help policymakers make informed decisions on contamination mitigation and provide insights into watershed management.

Impact of 5 waves of COVID-19 on pediatric ophthalmology.

OBJECTIVE: To characterize the impact of multiple waves of COVID-19 on pediatric ophthalmology at a tertiary care hospital. METHODS: Medical records were reviewed from pediatric patients seen for ophthalmic emergencies at the Montreal Children's Hospital (Montreal, Canada) from 5 COVID-19 periods: March 13 to May 31, 2020; September 20, 2020, to February 21, 2021; March 21 to May 31, 2021; August 17 to November 5, 2021; and December 19, 2021, to January 25, 2022, as well as 2 pre-COVID time periods: March 13 to May 31, in 2018 and 2019). RESULTS: There was a significant reduction in ophthalmic consultations when comparing pre-COVID to all 5 COVID waves (p < 0.0001). There was an increase in the average number of daily urgent (p = 0.01) ophthalmic consultations from waves 1 to 4. Mean household income of patients was not significantly different pre-COVID compared to during the 5 COVID waves (p = 0.96). The most common referral reason was ocular trauma (38.0% of cases). There was a non-significant trend demonstrating more infectious disease presentations during waves 3 to 5 (p = 0.07). There was no difference in symptom duration prior to presentation (p = 0.54); however, there was a difference in the time between emergency room and ophthalmology assessment in waves 3 and 4 compared with wave 5 (p = 0.003). CONCLUSION: The number of pediatric ophthalmology consultations was less during the 5 COVID waves than pre-COVID. An increase in urgent pediatric ophthalmology consultations occurred as COVID-19 infection rates in Quebec decreased. Access to health care and time to care were preserved across waves compared with pre-pandemic.

Incidence of difficult bag-mask ventilation in children: a prospective observational study.

BACKGROUND: Difficult airway (DA), including difficult bag-mask ventilation (DBMV), and difficult intubation (DI) is an important challenge for the pediatric anesthesiologist. While expected DBMV can be successfully managed with appropriate equipment and personnel, unexpected DBMV relies on the resources available and the experience of the anesthesiologist at the time of the emergency. The incidence and risk factors of unexpected DA in otherwise healthy children, including DBMV among pediatric patients are not known. The aim of this study was to expand the scientific knowledge of unexpected DBMV among pediatric patients. METHODS: Patients between the ages of 0 and 8 years, undergoing elective surgery requiring bag-mask ventilation BMV and intubation at the Montreal Children's Hospital were recruited in this prospective observational study. Data on the incidence of DBMV and risk factors were collected over a 3-year period. RESULTS: In a sample of 484 children, the incidence of unexpected difficult BMV was 6.6% (95% CI [4.6, 9.2]). The incidence of expected DA among the screened patients (N = 4865) was 0.5% (95% CI [0.3, 0.7]). In a logistic regression analysis, age (OR 0.98; 95%CI [0.97, 0.99]), undergoing otolaryngology (ENT) surgery (OR 2.92; 95% CI [1.08, 7.95]) and use of neuromuscular blocking agents (OR 3.49; 95%CI [1.50-8.11]) were independently associated with DBMV. The incidence of DI was 1.2%. No association between DBMV and DI was found (Fisher's exact test, P = 1.0). CONCLUSIONS: This is the first published report of the incidence of unexpected DBMV among healthy pediatric patients.